(A) Field of the Invention
The present invention is related to an electronic device, a transistor device and manufacturing methods thereof, and more specifically, to a printed electronic device, a printed transistor device and manufacturing methods thereof.
(B) Description of the Related Art
With the downsizing of electronic devices, because of natural limitations of light and requirement of high energy radiation, photolithography processes need more complicated and sophisticated equipment and techniques for the application of nanometer patterns. Consequently, there are shortcomings of high cost of equipment and high risk techniques. Domestic or international industrial and research fields all invest considerable capital and manpower in developing nanometer processes, intending to develop lower cost and more reliable techniques to meet the demand of equipment and technique for mass production of nanometer devices. However, for the lithography and etching processes, the costly reticle and equipment are still obstacles for entering the generation of 50 nm semiconductor processes.
Printing technique is convenient and simple, and can be performed by printing or transferring a pattern many times via a single mold. Printing is an additive process, so the waste of material can be significantly reduced. Besides, patterning for a large area can be subjected to printing for decreasing the cost.
The requirement of high speed of a printed transistor device can be accomplished by the following methods: (1) use semiconductor material of higher carrier mobility; (2) shorten the distance of source and drain of the transistor; or (3) use higher voltage.
The use of semiconductor material of higher carrier mobility is limited to the nature of the material itself, and thus the room for improvement is limited also. The use of high voltage cannot meet the requirements for the device of smaller line width of design rule as with the increase of circuit integrity. Consequently, shortening the distance between the source and drain becomes a solution in practice. It is important to associate with printing technique to obtain a transistor device of low cost and high resolution for current research and development.
U.S. Patent Publication No. 2004/0175963A1 and 2003/0059987A1 use either the characteristics of hydrophilic and hydrophobic or a barrier built in advance for ink printing, so as to fabricate the source and drain of the semiconductor transistor device.
WO 2004/055919 disclosed another method for fabricating a transistor device. Referring to FIGS. 1(a) and 1(b), two recesses 3 and 4 are formed in a substrate 1 by being pressed with a press mold 2, and are separated by a barrier 5. Then, a stamp 6 inked with a hydrophobic surface modifier 7 is pressed to contact the substrate 1, and thus the surface of the substrate 1 excluding the recesses 3 and 4 is daubed with the surface modifier 7 as shown in FIGS. 1(c) and 1(d). Referring to FIG. 1(e), because the surface modifier 7 is hydrophobic, conductive ink 8 only remains in the recesses 3 and 4 and forms a source 9 and a drain 10 when performing ink-printing. Sequentially, a semiconductor layer 11 and a dielectric layer 12 are formed on the surfaces of the source 9 and drain 10 in sequence, and a gate 13 is formed in the dielectric layer 12, by which a printed transistor device is formed as shown in FIG. 1(f).
The above known methods need to utilize hydrophilic and hydrophobic characteristics or use a barrier separating the recesses for the formations of the source and drain; thus the process is complicated and the manufacturing flexibility is decreased.